Optical communication networks are traditionally built upon a large network of optic cable links. These optic cable links consists of long and branched span of optical fibers. These optical fibers are generally joined together by splice connections or connectorization. Moreover, these optical fibers are also connected to various passive components like joint-closures, power splitters and filters. As the fibers are subjected through various splice, connector connections and bends, the optical signals in these fibers suffer losses. The optical signal suffers losses primarily due to attenuation of the fiber, apart from losses due to splice joints and connector joints. Optical fiber links are also subjected to bends e.g. macro-bends and stresses from cabling process.
Traditionally, optical time domain reflectometer (OTDR) is used to measure and characterize various loss events in the optical fiber link. Further, optical probing pulses are injected into these optical fibers. The optical probing pulses suffer from Fresnel reflections at various splice joints and connector joints. They also suffer from Rayleigh scattering along the length of the optical link and from macro-bends and stresses. The back scattered and back reflected pulses carry weak power and are detected by the sensitive receiver circuitry of OTDR. The OTDR measures the intensity of the back scattered optical signal and provides information of all loss events at various discrete points along the length of the optical fiber link.
In one of the prior arts, a method for intrusion detection in optical fiber is provided. The method and system disclosed in the prior art calculates insertion loss of the optical fiber which is sensitive to macro-bends, splice joints and connector joints. The prior art does not discuss any concrete method and system of differentiating macro-bend losses from splice joint and connector joint losses. The prior art does not derive any method or system that specifically mentions polarization dependent loss measurement as a mechanism to differentiate the macro-bends event signatures from splice and connector loss event signatures. In addition, the stated prior art and other prior arts are not very sensitive when it comes to identifying the macro bends in bend-insensitive fibers. They also require sophisticated algorithms and measurement time for testing of optical fiber links against macro-bend losses and therefore, they are unreliable for real time commercial applications.
In another prior art, the macro-bend losses are separately calculated using multi-wavelength OTDR. The multi-wavelength OTDR calculates macro-bend losses in the optical fibers. However, the multi-wavelength OTDR uses a multi-wavelength optical signal to probe the optical fiber against different losses. The use of multi-wavelength optical signal increases measurement complexity. The principle of operation of the multi-wavelength OTDR is based on the principle that macro-bend losses are a function of operating wavelength. The macro-bend loss increases exponentially with increase in operating wavelength. In addition, the measurement time increases in multi-wavelength OTDR as sophisticated algorithms are needed to process the multi-wavelength OTDR traces and are susceptible to fault tolerance.
High speed data transmission is more sensitive to the macro-bends in optical fibers compared to losses from splice joints and connector joints. Current monitoring methods are not able to distinguish between macro-bend losses from splice joint and connector joint losses.
In light of the above stated discussion, there is a need for a method and system that distinguishes macro-bend losses from splice joint and connector joint losses.